Time for valve stem seals... 2005, 4.4i, 113,000 miles
 

I actually have 16 plugs and 16 coils so when I ran in to the first error I literally just swapped in another plug and coil [emoji16]. When the error didn’t clear for that cylinder I pulled a good cylinder plug and coil and popped it in 8. After that cylinder 1, cylinder that I stole the plug and coil from, still showed ok while cylinder 8 still showed a misfire...


Checked the plugs, all gapped good and reseated the coils, still issues with 3, 6 & 8.

Also, about an hour into the diag and testing I started to get just the most faint bit of “tick” from under the passenger side valve cover. Faint... but still “tick,tick,tick”...

It’s not looking promising may have to pull that cover again at a minimum.

Going to go over everything one more time when I get home tonight and see what I see.

Check your grounds on the coils. Run some injector cleaner.

Wife's car started to misfire on one then another then another. After the second coil replaced it dawned on me: in 40,000 miles never ran injector cleaner.

Used a full bottle of Lucas injector cleaner on half tank of gas. Hasn't had a misfire since.


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Grounds on coils! Good call! I had one of the valve cover ground bolts freeze on me, actually had to cut the wire and grind the bolt head off... I reset and re-solder everything- let me walk back through all that before I get back in to pulling covers...

Injector cleaner is part of my “religion” [emoji16]. I run a bottle of the stuff through each of my cars on a rolling 4 month schedule - sucker was purring like a kitten (aside from all the smoking), before I tore it apart.

Crazy thing... I triple checked each valve, seal, rocker and eccentric before I buttoned it up. I even went to the extreme of turning the engine over a full firing cycle as I finished each valve just to try and isolate any lingering issues...

I guess it comes down to “crap happens”... darn!

Misfires are usually a coil connection problem. Sometimes the ground if it doesn't move as you move the coil. If it jumps around, it's usually the coil plug interface.



Most often it seems to be the coil rising off the plug as the engine runs. That's often from using dielectric grease on the plug. It's not needed on these connectors and will cause hem to unseat.




From the FAQ here:


https://www.boschautoparts.com/en/au...ignition-coils

Nothing under the cover that i can think of will cause the symptoms you describe. Get some deoxit gold for your contacts.


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Agreed. Can confirm that Deoxit is the best.

Unfortunately, according to Tony of AGA tool rental service, it's possible to inadvertently install the keepers upside down in a couple of valves and not notice it, especially if you're in a hurry. Everything moves and appears fine when hand cranking but upon running the engine, persistent misfires is the result.

Starting from 12th minute in his video demonstrates the issues.
https://youtu.be/-1D29BW-xbQ?t=707

Time for valve stem seals... 2005, 4.4i, 113,000 miles
 

Very interesting about upside down keepers. It should have been very obvious like in the video if the valve stuck out a long way past the spring.

If you took photos you can verify or use the fiber optic camera on the right side through the oil fill.

I am going to go back through all of my electrical connections, coils and plugs tonight before I get in to anything else for sure.

I guess it’s possible to flip a keeper but as I checked each valve I looked for a nice flush mate where the keeper touched the spring lock/cap and for very little valve stem protruding above that - I was as sure as the miss I have now that I had everything buttoned up properly.

I may play the coil game, pull them all, clean them up (again) and reinstall them randomly as my new baseline and see what that gets me. If still cylinders 3, 6 @ 8... well...

Man I REALLY HOPE it’s as simple as (re)fixing the ground I clipped and making sure it has a solid contact.

Thanks for all the great ideas, I will keep you guys posted for sure.

Did you check that the timing sensor plates were tight? There is a current threat where that plate got loose it could cause lots of misfire. Not sure how I would not affect all cylinders but the thought just crossed my mind.



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